Where do we find debris on land?

It's everywhere, but only over the last decade have we started to make debris data accessible over the web. Use the Debris Tracker data source to visualize debris found on land:

VISUALIZE DEBRIS

1. Specify a time period to query using the time period specification box in the form (e.g. 9/1/2023 - 9/30/2023).
2. Draw a geospatial selection area in the map (e.g. Eastern Massachusetts)
• Use the geospatial selection drawing toolset at top left.
• You may only use polygon or rectangle drawing options for geospatial selection.
• There must only be one area drawn when requesting data.
3. Click the drawn area and select the data source (e.g. "Debris Tracker")
4. From the list that appears in the pop-up, choose the "position" parameter to query.
5. Close the data selection pop-up using the 'x' at top-right, and clear the drawn selection area by clicking 'Delete Layers' in the geospatial selection drawing toolset.

Where might it have come from?

You can start to understand the flow of debris into a point by examining its watershed, the area around a point from which rainfall and snowmelt flow to it.

DRAW WATERSHED

Use the Draw Watershed tool to automatically draw the watershed for any land-based point on the map.

To use, click the tool icon to enable it, then click any point on land (e.g. where you found some debris using Debris Tracker) to automatically draw the watershed. This tool uses a national digital elevation model to generate a result.

Point selection triggers submission of a job to ESRI, and it may take several seconds for a response to be returned and drawn on the map.

How could it find its way to the ocean?

While it's hard to predict the exact path (there are lots of variables), we can visualize the flow of debris following the natural topography of the land.

TRACE DOWNSTREAM

Use the Trace Downstream tool to automatically trace the natural path to the ocean from any land-based point on the map.

To use, click the tool icon to enable it, then click any point on land (e.g. the same point at which you drew a watershed) to automatically trace the downstream path. This tool uses a national digital elevation model to generate a result.

Point selection triggers submission of a job to ESRI, and it may take several seconds for a response to be returned and drawn on the map.

The downstream flow of a particle follows rivers and streams. You can visualize rivers and streams in the map by using the Layer Control to toggle 'Hydrography', then either 'Massachusetts' or 'Rhode Island'.

Once in the ocean, where might it go?

Ocean drifters are excellent "tracers" for understanding the flow of surface debris. Fortunately, there are vast databases of drifter tracks to help us with this, such as the one hosted by the Student Drifter Program. Let's visualize a large number drifters, so that we can see related patterns (currents, ocean temperature, etc.):

VISUALIZE DRIFTERS

1. Specify a time period to query using the time period specification box in the form (e.g. 1/1/2016 - 12/31/2016 or later).
2. Draw a geospatial selection area in the map (e.g. Massachusetts Bay)
• Use the geospatial selection drawing toolset at top left.
• You may only use polygon or rectangle drawing options for geospatial selection.
• There must only be one area drawn when requesting data.
3. Click the drawn area and select the data source (e.g. "SDP Drifters")
4. From the list that appears in the pop-up, choose the "position - ALL" parameter to query.
5. Close the data selection pop-up using the 'x' at top-right, and clear the drawn selection area by clicking 'Delete Layers' in the geospatial selection drawing toolset.

Use the Layer Control to toggle the drifter track points on. Each point contains the corresponding time, which we can use to relate to currents! For example, note the times along a drifter track when it makes abrupt turns.

NOTE: The animated tracks for active drifters that appear when the page loads are represented by an animated line and transparent track points; hover the cursor over the line vertices to see track point information.

These drifters flow in unpredictable ways due to the complexity of forces affecting them, such as eddies, currents, tides, and wind. To visualize flow, let's use the interface to submit queries for currents and sea surface temperature, and compare these data to drifter movement using the drifter track point times.

VISUALIZE CURRENTS

1. Specify a time period to query using the time period specification box in the form (e.g. 7/1/2023).
2. Draw a geospatial selection area in the map (e.g. Massachusetts Bay)
• Use the geospatial selection drawing toolset at top left.
• You may only use polygon or rectangle drawing options for geospatial selection.
• There must only be one area drawn when requesting data.
3. Click the drawn area and select the data source (e.g. "MARACOOS")
4. From the list that appears in the pop-up, choose either the Doppio ROMS daily current prediction options to query
5. Close the data selection pop-up using the 'x' at top-right, and clear the drawn selection area by clicking 'Delete Layers' in the geospatial selection drawing toolset.

VISUALIZE SEA SURFACE TEMPERATURE

1. Specify a time period to query using the time period specification box in the form (e.g. 7/1/2023 - 7/31/2023).
2. Draw a geospatial selection area in the map (e.g. Massachusetts Bay)
• Use the geospatial selection drawing toolset at top left.
• You may only use polygon or rectangle drawing options for geospatial selection.
• There must only be one area drawn when requesting data.
3. Click the drawn area and select the data source (e.g. "PODAAC")
4. From the list that appears in the pop-up, choose the "MODIS L3 - NSST - 4km - 8day (°C)" parameter to query
• You have options for visualizing night time Sea Surface Temperature (SST) averaged products over different time spans, including 8-day, monthly, and annual averages
• Longer time period specification and shorter SST averaging periods lead to longer querying and render time.
• All of the SST products in this interface use 4km-resolution nighttime measurements collected by the MODIS sensor, which is mounted on the Sun-synchronous Terra satellite.
• The color palette extent of the response is set to the global SST range by default. To make your SST response color palette more intense, use the Extent toggle in the Frameset Control to switch from 'global' to 'local' extent.
5. Close the data selection pop-up using the 'x' at top-right, and clear the drawn selection area by clicking 'Delete Layers' in the geospatial selection drawing toolset.

This interface was developed using the Seaglass framework for network-based data visualization.

Point of Contact

For questions and comments, contact:

Ben Bray, MIT Sea Grant